Mariner 6

[concentrik]

Mariner 6 (twin) year 1990-1994, not firing on upper cylinder, lower fires OK. Compression good on both. Fuel through to both. New plugs - combustion signs clear on lower but upper is totally clean - no combustion. Ignition coils swapped without effect (fault remains on upper cyl). Plug leads swapped - no effect. CDI unit replaced - no effect. All connectors are good.

Resistance tests show trigger: 752 Ohms (ok according to manual)
High speed coil: 140 Ohms (manual says 750-1400)
Low sped coil: 3300 Ohms (ok according to manual)

I can't get the flywheel off. The retaining nut is off but my puller (three bolts on a plate screwed into flywheel tapped holes, centre pressure bolt) won't pull it off even with gentle to moderate tapping.....

So here's the questions at last: does the charge coil (stator) drive each cylinder separately or does it simply provide a current which is then sent to each plug by the CDI unit on trigger command? I'm thinking that if the stator coil does NOT have a unique relationship with each cylinder it cannot be the cause of a failure appearing on only one cylinder....

I suppose it's possible that the trigger coil is not producing the positive pulse to fire the number one SCR but it IS producing the negative spike to fire the number 2 SCR. How likely is this and is it possible to test without a 'scope? (Which I stupidly sold thinking I wasn't going to need it after giving up electronic servicing!!). I have a Fluke digital meter which will read neg but I think the pulse may be too short? Because I'm having so much difficulty removing the flywheel I'd like to be as sure as possible that the fault lies with trigger/stator before proceeding with removing it.

Sorry for the long post - and I realise this may need quite in-depth knowledge of CDI ignition systems so please feel free to point me to a more specialised board if there is one!!

Many thanks

Andy
Dorset, UK

Still on the hard when everyone else in our little harbour is in the water.... Grrrrr!

 

[Laddies]

Re: Mariner 6

Both the stator and the trigger serve both cyls, so the problem is either a coil or switch box or the wire in betweem, that make it easy to trouble shoot with out proper tools, just swap the lead wires to the coils at the box and if the problem switches cyls. it's the box and if it stays the same it's the coil or one of the wires that serves that coil.

 

[concentrik]

Re: Mariner 6

OK I didn't realise you could do that..... I thought that the input from the trigger was either negative going or positive going and that fired the number one cylinder or number two cylinder. Won't swapping the box outputs cause the cylinder to fire at the wrong point in the stroke, i.e. where the opposite cylinder should be firing?

Thanks,

Andy

 

[Laddies]

Re: Mariner 6

Andy, you hook the plug wires to a spark gap of some type when testing, yes the trigger winding and coil windings do pulse - & + but the coils are really transformers and react to either voltage pulse here's a schematic for the system it will help you understand it. If the trigger or stator windings have a open the system won't pulse either way as each is the the other ends ground.